Background: Substance use disorders (SUDs) are complex conditions influenced by a myriad of 
factors, including psychological, social, and biological elements. While previous research has delved 
into the connection between substance use and attachment types, as well as the role of defense 
mechanisms in addiction, a comprehensive understanding of the underlying mechanisms remains 
elusive. By examining the intricate connections between attachment, emotional regulation, and defense 
mechanisms, this study seeks to advance the field of SUDs research and inform the development of 
more effective treatment modalities. Aim: This study investigated the mediating role of emotional 
regulation in the relationship between attachment styles and defensive coping among clients with 
substance use disorder (SUD). Subjects and Method: Design: The research design used for this study 
was a descriptive correlational one. Subjects: A convenience sample of clients with SUDs in the 
outpatient units of El-Maamora Hospital for Psychiatric Medicine was followed. Tools: Four 
instruments utilized to collect the data (socio-demographic data, Revised Adult Attachment Scale 
(RAAS), Defense Style Questionnaire (DSQ), and Emotion Regulation Questionnaire (ERQ). Results:
Current findings indicate that defensive styles are strongly correlated with attachment style and 
emotional regulation in clients with substance use disorders. Clients with secure attachment tend to have 
better emotional regulation, which in turn contributes to lower levels of immature defense styles.
Conclusion and Recommendation: Interventions targeting attachment insecurity, promoting the 
development of mature defenses, and enhancing emotional regulation skills may be beneficial in treating 
SUDs. Psychiatric mental health nurses should develop psychoeducational programs for parents and 
teachers to enhance emotional regulation and child attachment security as prevention strategies